Currently: A very chaotic wx picture across the NE quarter of the US. One frontal zone is offshore with low pressure off ACK. Another frontal zone is across the Appalachians, with lows along that front. That frontal zone seems to be progressing slower than fcst and that will have to be watched for purposes of tonight's fcst. A tertiary front, the one that will actually bring the cold air with it, is moving thru the Michiana region right now.
Tonight: As mentioned, it's a bit of a difficult fcst regarding what time the front goes thru, and alas, what time lingering showers end and skies clear. For now, will still go with rain ending in the mid afternoon and clearing a few hrs later. That will allow temps to plummet with cold air advection, and lows should range from the mid teens to the mid 20s, except maybe a few degrees warmer along the immediate SE Coast, where clearing might take longer. I could be off by a few hrs and if I am, temps will end up a few degrees warmer than fcst.
Tomorrow: Clear and much colder with arriving cold air advection. I'll run with the cooler GFS guidance, as it seems to have a better handle on arriving cold air. Don't expect temps to rise much tomorrow, esp in areas that started warmer. Expect highs within a few degrees of 30, and a breeze to make it feel even cooler.
Tomorrow night/Saturday: Possibly the coldest air mass of the season. Places in the NW hills and NE CT away from the cities probably start below 0. We do moderate fairly well during the day on Sat, however. In fact, I think we outperform guidance by a couple degrees, due to a downsloping component to the wind. Highs should wind up within a few degrees of the freezing mark, but it could be a degree or two warmer along the I 91 corridor.
Long Term (Sunday and beyond): All in all, the long term is biased cooler than we have been, but warm in the middle, when a storm passes thru. I'll split the long term into two sections- before and after storm. First, a warm front will move thru late Sat night into early Sunday morn. This front has almost no lift with it, but a brief flurry cannot be ruled out. Sunday is warmer, and guidance will generally be accepted. High temps should generally be 40-45, again a tad warmer possibly along the I 91 corridor. Monday should be a touch cooler, as a little lobe of high pressure crests over Srn Canada and funnels just a touch of cool air into the area. Highs should be near 40, but mid 30s N of I 84.
The next system will approach the area Tuesday. This system has been trending slower, and I will not buck the trend. I'll keep Tuesday dry and focus the rain on Tuesday night after mid-evening and end it by dawn on Wed. It is not a huge system- more of just a frontal passage. Guidance looks good for Tue's temps- and we'll go with highs in the mid to upper 40s- close to guidance.
Colder air moves in on Wednesday behind the storm system, along with wind gusts to at least 40 MPH. Once again, I have no quibbles with temp guidance, so will generally follow. High temps should be around 40 degrees. Colder air seeps in for Thu. Here is where I will go a good 5 degrees below guidance, as model guidance has trouble resolving strong cold air advection this far out. That said, expect highs around 30 degrees. Once again, at this time, the cold shot appears transient, with another storm system slated to affect the area with more rain a few days down the line.
Long Range: The long range pattern is starting to show hints of a generally cooler pattern, as the mean SE Ridge gradually gets beaten down with time. There may be time to even salvage a month of winter for snow-starved snow lovers! Of course, the later we head into the season, the more the interior becomes favored.
Now, let's look at some systems slated to affect the area this week. This section will be "lighter" than normal, since after today, there's really only one system slated to affect the area with any measurable pcpn. So let's take a look at the Tue night front.